While the natural history of human lung function growth and decline has been studied intensively over the past 30 years, relatively few data have been collected during the period in which peak volumetric function is achieved, i.e., around the age of 20. As a result, very little is known about the factors, both demographic and environmental, which influence maximal attained lung function. The proposed study will measure lung function and respiratory symptom status on a large cohort of healthy, non-smoking 18-22 year old subjects, and relate these measurements to past histories of passive smoke and air pollution exposures. The study population will consist of one class of approximately 1000 cadets at the U.S. Military Academy at West Point, NY. Information on the history of respiratory illness, residential history, parental smoking, socio-economic status and home characteristics will be collected via an initial questionnaire administered upon enrolling at West Point. A sequence of four annual measurements of lung function (by spirometry), and prior-year respiratory health status and activity patterns will be obtained in the spring of each year. Pollution exposures will be estimated by matching residential histories with historical pollution data stored at EPA. Data on meteorological variables (temperature, relative humidity, wind speed) and altitude will be obtained for each residential location. The four annual lung function measurements will provide precise estimates of individual mean levels of FVC, FEV1, FEF25-75, PEFR, and flow rates at 50% and 75% of expired FVC. Subject-specific lung function level will be analyzed in relation to history of parental smoking and prior exposure to air pollution using analysis of variance methods, controlling for potential confounding variables. In addition to testing these hypotheses regarding the respiratory effects of passive smoking and air pollution exposure, this study will also explore the effects of these exposures on the change in lung function between the ages of 18 and 22 and on respiratory illness and symptom experience while at West Point. Finally, this study will establish a cohort which can be followed in future years.